The present invention relates to a sample support which fixes a minute sample such as a TEM viewing sample which is pinpoint-sampled and facilitates additional forming.
Conventionally, with respect to a technique for performing a pinpoint sampling which cuts out a minute sample piece from a specific portion of a sample using a focusing ion beam (FIB) device and for fixing the sample piece to a sample support, various types have been proposed. For example, there have been proposed 1) a method in which a portion of a wafer containing a specified part is mechanically cut out into a block shape and the block is sliced by FIB forming, 2) a method in which holes are formed in portions in front of and behind a specified portion of the wafer by FIB, the thin-piece finish forming is applied to the wafer by FIB, and formed samples are transferred to a mesh and are fixed to the mesh (a lift-out method, see patent document 1), 3) a method in which holes are formed in portions in front of and behind a specified portion of the wafer by FIB and, then, samples in a form of a minute block are picked up and are fixed to a sample support and, thereafter, are subjected to the thin-piece finish forming by FIB (see patent document 2). Since the sample is formed by dicing in the method 1), drawbacks such as the occurrence of cracks and chipping arise and even when the expertise is available, the thickness obtained by thickness forming is limited to 10 μm. With respect to the method 2), the sample piece is ultra-fine and hence, once the sample piece is lost, it is impossible to recover the sample piece and, at the same time, reforming after the pickup operation is impossible. The method 3) which picks up the sample piece in the form of the fine block necessitates a cumbersome operation which requires an expertise. That is, in the method 3), the sample piece is picked up in a fine block form, the fine block is once fixed to a distal end of a probe which is manipulated by a micro manipulator by a FIBCVD, is transferred to a sample support and, thereafter, is separated by cutting.
In non-patent document 1, a method 3) which can perform reforming is disclosed. The method 3) prepares the sample as follows. Since the method 2) which adheres the lift-out sample to the carbon mesh cannot perform the reforming, first of all, a sample support which replaces the mesh is prepared. That is, a Si wafer is polished until a thickness of the Si wafer becomes close to 10 μm by dicing and, thereafter, grooves which prevent the Si wafer from becoming an obstacle in the transmission of electrons at the time of performing the TEM observation and a wall for hanging the lift-out sample are formed in the Si wafer by FIB thus forming a sample support a shown in a left upper portion of FIG. 7. Although the steps until the sample is lifted out is similar to corresponding steps of the lift-out method, it is necessary to perform additional forming after the lift-out step and hence, the FIB forming applied to the sample is temporarily finished while leaving an observation portion having a thickness of 2 to 3 μm. A fine sample piece opening (observation portion) is lifted out from the FIB forming portion by manipulating a micro-manipulator and the fine sample piece opening is hung from the above-mentioned sample support a which is prepared from the Si wafer (a state shown in a right upper portion of FIG. 7). The fine sample piece opening which is placed on the sample support a is again returned to the FIB forming part together with the sample support (a state shown in a left lower portion of FIG. 7), and both ends and a bottom of the sample b are fixed to the sample support b by the FIB deposition using tungsten or the like (a state shown in a right lower portion of FIG. 7). When the sample piece opening is fixed, the reforming for thinning is applied to the sample again.
In applying the additional forming to the sample obtained by the pinpoint sampling, there have been proposed ideas such as the large-sizing of the sample support for lowering a background of the sample support such as mesh, the reduction of thickness of the mesh for reducing a forming portion, and the reduction of a thickness of a portion on which the sample is placed by preparing the sample support by dicing. However, when the thickness of the mesh is reduced, the handling of the mesh becomes difficult and the mesh decreases strength and hence, the mesh is readily bent. Further, a surface of the mesh formed by etching is not uniform and includes waviness and irregularities and hence, the mesh is not suitable for fixing the minute small piece vertically. Further, when the sample support is prepared by forming the Si wafer by dicing, it is possible to prepare the high-quality sample support. However, the dicing is performed manually and hence, the dicing requires the expertise whereby there has been a drawback that it is difficult to manufacture the sample supports on a mass production basis thus pushing up a cost. Further, the dicing forming is liable to cause chipping (cracks and chipping) and hence, it is difficult to set a width of the sample fixing surface to 10 μm or less even with maximum efforts and hence, the width of the sample fixing surface is set to approximately 20 μm. In preparing the TEM sample, to lower the background of the sample support, the sample support is also etched and hence, when the sample support is thick, there has been a drawback that the forming time is prolonged corresponding to the thickness.    [Patent document 1] JP-A-2001-141620 “Cut forming method of sample for transmission electronic microscope” which was laid open on May 25, 2001    [Patent document 2] JP-A-2003-35682 “Sample holder and sample analyzing method” which was laid open on Feb. 7, 2003    [Non-patent document 1] Daisuke Sakata, “FIB lift-out method which enables additional forming” “Written Summary of Lectures presented in the 58th Meeting of Japan Electronic Microscope Society”, page 247, May 14 to 16, 2002, Japan Electronic Microscope Society”
The task to be solved by the present invention is to provide a sample support which can perform additional forming of a sample without giving rise to a drawback on flatness of a surface of a mesh, for example, and on the generation of background noises and can fix a thinned sample without requiring an expertise in preparing the sample.